Field of the Invention:
The present invention relates to an electric cable including a multilayer insulation made from silicone rubber, as well as a manufacturing process of said electric cable.
More particularly, it applies typically, but not exclusively, to the fields of power cables, such as medium voltage (especially from 5 kV to 45-60 kV) or high voltage (especially greater than 60 kV, which may be up to 800 kV) power cables, whether they are direct voltage (DC) or alternative voltage (AC) cables.
Description of Related Art:
Medium voltage or high voltage power cables typically comprise a central electric conductor and, successively and coaxially around this electric conductor, a semiconducting inner layer, an electrically insulating (intermediate) layer and a semiconducting outer layer. These three layers can be crosslinked via techniques that are well known to those skilled in the art.
GB 870 583 describes a 3-layer insulation for an electric cable, comprising a semiconducting inner layer, an electrically insulating (intermediate) layer and a semiconducting outer layer. Said three layers are made from vinyl-containing silicone gum, and are extruded successively around an electric conductor to form said 3-layer insulation.
However, this process is not optimized to reduce significantly partial discharges between the electrical insulating layer and the semiconducting layers, when a voltage level of at least 5 kV is applied to the electric cable.